Coaxial connector

ABSTRACT

A coaxial connector for making an electrical connection through the wall of an enclosing box to a printed circuit board. The connector has one end formed in conventional fashion to mate with a cable connector, while the other end which extends through a clearance hole in the enclosing wall, has an outer cylindrical conductor flatted on two sides and a central conductor embedded in insulating material and extending beyond the end of the outer conductor. The slots in the outer conductor interconnect the flatted portions and a bracket has a pair of tabs extending out from a U-shaped portion, the U-shaped portion fitting through the slots to retain the connector within the enclosing wall, the tabs supporting the printed circuit board and providing an electrical connection to the ground plane thereon. A retaining ring threads on the opposite end to fasten the conductors from outside the wall.

' 0 United States Patent [191 [111 Patterson Jan. 1, 1974 COAXIAL CONNECTOR Primary Examiner-Bernard A. Gilheany [75] Inventor: William L. Patterson, Berlin, Mass. Ii i s [73] Assignee: Adams-Russell (10., Inc., Waltham,

ass 57 ABSTRACT [22] Flled: 1972 A coaxial connector for making an electrical connec- [21] Appl. No.: 237,326 tion through the wall of an enclosing box to a printed circuit board. The connector has one end formed in conventional fashion to mate with a cable connector, [521 317/101 174/65 7 52 while the other end which extends through a clearance [5]] 1m Cl 02b 1/02 hole in the enclosing wall, has an outer cylindrical [58] Fieid 65 R conductor flatted on two sides and a central conduc- 317/101 R R tor embedded in insulating material and extending be- 14 126 126 j yond the end of the outer conductor. The slots in the outer conductor interconnect the flatted portions and bracket has a pair of tabs extending out from a U- 56 a 1 References cued shaped portion, the U-shaped portion fitting through UNITED STATES PATENTS the slots to retain the connector within the enclosing 2,236,130 3/l94l Betebenner 174/5] UX wall the tabs supporting the printed circuit board and gg g l lg providing an electrical connection to the ground plane l erson Cl. a

thereon. A retaining ring threads on the opposite end to fasten the conductors from outside the wall.

7 S CIaims, Q Prawing Figures 1 COAXIAL CONNECTOR FIELD OF THE INVENTION This invention relates in general to electrical connecstruction for use with printed circuit boards.

BACKGROUND OF THE INVENTION In the packaging of electrical circuits, particularly circuits for operation at radio frequencies and higher, it is usual to enclose the circuitry within a sheet metal box and to interconnect the enclosed circuits by means of coaxial cables between the boxes, the cable connecting to each circuit through a coaxial connector mounted to the wall of the box and providing a connection through the wall of the box for both the center conductor and a ground connection to the outer sheath of the cable. In many instances the circuitry within the sheet metal boxes is in the form of printed circuit boards to which components may be attached, or the circuit may include microstrips having a ground plane on one side of a insulating board and an electrical conductor on the opposite side. In most configurations of these circuit boards within the enclosing box, the connection between the coaxial connector and the box is edge on since the two conductors from the coaxial connector are to be connected to opposite sides of the board. The requirements for such a connector include the mechanical requirements of being fastened securelyto the box and being able to withstand the mechanical twisting applied to the connector to fasten the cable to it in addition to the electrical requirements of establishing a good ground connection between the sheath of the coaxial cable and the ground plane of the circuit board. At frequencies above 400 megahertz the ground connection must be short in order not to introduce signal distortion problems.

In the past, the usual form for such a connector has been a coaxial cylindrical type of connector in which a center pin is embedded within and extends beyond a cylinder of insulating material with a coaxial cylindrical collar fitted over the insulating material, the collar carrying a flange for mounting to the wall of the sheet metal box. A clearance hole is cut in the wall of the sheet metal box to allow the cylinder of insulating material to extend into the box and the flange is screwed to the outer wall of the box through holes drilled in both the flange and the box. There are a number of problems associated with this arrangement. These include the difficulties of providing for continuous electrical ground connection from the ground plane of the printed circuit through to the outer sheath conductor of the cable, the requirement for maintaining hole tolerances for the mounting holes and the limitations on methodsby which the connector may be mounted to the box, since the thin sheet cannot provide resistance against rotation of the connector merely by including a flat on one side of the cylindrical outer conductor of the connector. In the conventional approach, a ground connection is typically made through the wall of the enclosing box and accordingly there must be provided good electrical connection between the flange and the boxs outer surface, with the latter providing a continuous conducting path through to an inner connection made to the ground plane of the circuit board. In some instances foil has been used in order to obviate the requirement of a conducting surface of the box, thereby permitting the box to be anodized or painted prior to mounting of the connector. in this conventional approach there are additional problems concerned with mounting of the printed circuit boards within the box, the usual approach being one involving fastening mounting brackets to the wall and also to the ground plane side of the printed circuit. Many of the techniques employed with this conventional approach are unsatisfactory for very high frequency circuits since the length of the ground path is excessive and, in some instances the continuity, depending upon screw connections and the like, is insufficient.

BRIEF SUMMARY OF THE INVENTION Broadly speaking, in the present invention a coaxial connector for mounting through the wall of an enclosing box to the edge of a printed circuit board or microstrip includes one element formed of an outer, generally cylindrical, conducting sheath enclosing a cylinder of insulating material with a center conductor pin running through it. The outer conductor sheath is formed with flats on two opposing sides and a pair of slots running along opposite sides interconnecting each of the flats. This connector element is passed through a clearance opening of similar shape in the wall of the box and is maintained in position through the wall of the box by means of an electrically conductive bracket element having one portion flush with the wall of the box and including two parallel extending arms which slide through the slots in the cylindrical sheath thereby preventing the connector element from being withdrawn from the box. At its outer end the cylindrical sheath conductor of the connector element is threaded and a threaded retaining ring is screwed along this connector and tightened against the outer wall of the box. The further end of the connector, outside of the box is formed as a conventional coaxial connector designed to mate with the appropriate connector on a coaxial cable.

The bracket on the inner wall of the box contains two tabs formed at right angles to the plane of the box wall and positioned so that they are displaced from the plane of the connector by a distance approximately equal to the thickness of the printed circuit board. The printed circuit board is therefore supported on the pro truding tabs and the ground plane is soldered to them to form a short direct electrical connection to the outer sheath of the connector and thence to the other sheath of the coaxial cable. The center pin of the connector is soldered to a printed circuit conductor on the upper side of the printed circuit board and the circuit board is mechanically supported in position by being caught between the protruding tabs on the bracket and the center pin of the connector.

With this arrangement, not only is the printed circuit board adequately supported within the box, but also all the electrical connections to the connector are made within the box, thereby permitting that the exterior surface may be anodized, painted, or coated without regard to its electrical conductivity. Since the only open- DESCRIPTION OF THE DRAWINGS In the drawing:

FIG. 1 is an exploded view of a connector constructed in accordance with the principles of this invention;

FIG. 2 is a perspective view of a connector of this invention mounted in place and connected to a printed circuit board; and

FIG. 3 is a perspective view of an alternative embodiment of a bracket constructed in accordance with the principles of this invention.

DESCRIPTION OF PREFERRED EMBODIMENTS In FIG. 1 the elements of the connector of the invention are shown unassembled with respect to a portion 14 of the wall of an enclosing electrical box. A cylindrical connector element 1 is formed with a center conducting pin 2 extending beyond the face of a cylinder of insulating material 4. The coaxial outer cylindrical sheath 7 is formed of electrically conducting material and includes a threaded portion 8 at one end. The threaded portion 8 of the connector element I has a pair of opposing flat surfaces 9 interconnected on each side by a pair of slots 6. A lock washer 13 and threaded retaining ring 12, which serves as a retaining member form a part of the connector element 1. The box wall 14 includes an opening 16 shaped to conform to the cross sectional shape of the end of the connector element 1, the dimensions of the opening 16 being sufficiently larger than those of the corresponding portions of the connector element 1 to provide for clearance passing the connector element 1 through the opening 16. A bracket member 22 is formed to cooperate with the connector element 1 to retain that connector element in position within the box and to provide both electrical ground connections to a ground plane on a circuit board and also to provide mechanical support for the circuit board. Bracket 22 includes a generally flat portion 23 having a pair of extending legs 24 in the same plane as the portion 23 and a pair of tabs bent at right angles to the plane of the flat portion 23. An opening 25 in the bracket is of sufficient size to allow the inner end of the connector element 1 to pass through it.

As is more clearly illustrated in FIG. 2, the assembly of the elements illustrated in FIG. 1 is such that the connector element 1 is inserted through the opening 16 with the extensions 24 of bracket 22 being passed through the slots 6, the resultant assembly thereby being fastened against withdrawal of the connector from the opening 16. The retaining ring 12 is then screwed up tight against the outer wall of the box 14 fastening the entire connector element I firmly in place. Since the bracket 22 is formed of the conducting material, then the outer sheath 7 of the connector element 1 has a direct electrical connection to the tabs 20 of the bracket 22.

As is shown most clearly in FIG. 2 an electrical circuit board 28, which typically would be formed with a ground plane 34 in its lower surface and a pattern of printed circuit conductors 26 on its upper surface is positioned between the center conductor pin 2 of the connector and the tabs 20 of the bracket 22. By soldering the ground plane to the brackets 20 and the center conductor pin 2 to the printed circuit pattern 26, direct electrical connections are made both for the ground connections and for the center conductor connections of the coaxial connector. The spacing between the flat 9 on the connector element 1 and the center pin 2 is such that, cooperating with the spacing between the tabs 20 and the upper edge of the opening 25 and bracket 22, the gap in the assembled connector between the center pin and the tab 20 is just sufficient to allow the thickness of printed circuit board to be inserted therebetween and the overall assembly therefore provides for mechanical support of the circuit board as well as for the electrical connections to it.

In FIG, 3 there is illustrated an alternative form of bracket 22, here designated 22. In this embodiment the flat portion 23' of the bracket is formed generally as in the case of the bracket 22, however the tabs 20 are replaced with a lip member 30. When the connector is assembled with this bracket, the bracket is assembled to the connector from below with the lip 30 providing support for the printed circuit board 28 and providing for the ground connection to the ground plane 34.

What is claimed is:

l. A coaxial connector for connecting printed circuit boards within an enclosing wall to coaxial cables on the other side of said wall, comprising:

a connector element having a generally cylindrical outer conductor with two slots cut therein and a coaxial center conductor separated from the outer conductor by an electrically insulating material;

a retaining member fastened over one end of said connector element;

an electrically conductive bracket placed around the other end of said connector element engaging said outer conductor through said slots, said bracket including supporting means for mechanically supporting said printed circuit board and providing an electrical connection between a conductor on one surface of said printed circuit board and said outer conductor on said connector element.

2. A connector in accordance with claim 1 wherein said outer conductor of said connector element has a portion of its surface flatted.

3. A connector in accordance with claim 1 wherein said bracket includes a first portion which engages said slots by sliding along said slots, with and wherein said supporting means comprises two parallel tabs extending in the direction normal to the first portion of said bracket.

4. A connector in accordance with claim 1 wherein said supporting means comprises a lip extending from said bracket and upon which said printed circuit can rest.

5. A connector in accordance with claim 1 wherein a portion of said outer conductor is partially threaded near said one end and said retaining member is threaded to engage said outer conductor threads. 

1. A coaxial connector for connecting printed circuit boards within an enclosing wall to coaxial cables on the other side of said wall, comprising: a connector element having a generally cylindrical outer conductor with two slots cut therein and a coaxial center conductor separated from the outer conductor by an electrically insulating material; a retaining member fastened over one end of said connector element; an electrically conductive bracket placed around the other end of said connector element engaging said outer conductor through said slots, said bracket including supporting means for mechanically supporting said printed circuit board and providing an electrical connection between a conductor on one surface of said printed circuit board and said outer conductor on said connector element.
 2. A connector in accordance with claim 1 wherein said outer conductor of said connector element has a portion of its surface flatted.
 3. A connector in accordance with claim 1 wherein said bracket includes a first portion which engages said slots by sliding along said slots, with and wherein said supporting means comprises two parallel tabs extending in the direction normal to the first portion of said bracket.
 4. A connector in accordance with claim 1 wherein said supporting means comprises a lip extending from said bracket and upon which said printed circuit can rest.
 5. A connector in accordance with claim 1 wherein a portion of said outer conductor is partially threaded near said one end and said retaining member is threaded to engage said outer conductor threads. 